HAVERHILL — Cheering for the collapse of a bridge isn’t something you’d normally encounter. But at the Haverhill Alternative School, teams of students competed to see whose bridge made of pasta would fail and collapse first after hanging heavy loads from them.
It was a competition to see whose bridge was the strongest by design and just how much weight they could bear before crashing to the floor.
“The project emphasizes tension, compression, torsion and shear, but it’s really all about breaking stuff,” science teacher Neil Wilkins said with a smile.
Wilkins teaches a unit on engineering and technology to his high school students at the Alternative School, located on the second floor of the St. James school building on Primrose Street.
During a recent hands-on project, he asked his students to plan, draw and build a bridge prototypes made from one pound boxes of spaghetti strands, using hot tape and glue so their bridges would support the greatest possible load, over a minimum one-foot span.
“Spaghetti bridge building exercises are widely used in national engineering programs to demonstrate the structural possibilities of enhancing seemingly ‘weak’ materials through engineering design,’” Wilkins said.
His students based their bridges on Warren truss and Pratt truss designs, which incorporate triangular structural components, and the arch bridge, an ancient design with abutments at each end. A few years ago he challenged his students to use plastic drinking straws to build the longest bridges they could before collapsing, and prior to that they built tall towers.
Students and staff gathered in the school’s science and art room last week and eagerly watched as Wilkins began testing the strength of six bridges built by teams of students. Using classroom desks as abutments, Wilkins placed a wooden stick across the width of Wilgen Montero’s bridge and carefully suspended the bucket beneath with string.